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Carving to deep!

My Z axis is carving to deep. when I design something to cut all the way through and leave tabs. It ends up cutting all the way through and carving the tabs in my spoil board. In easel I set it up to cut using multiple passes to the exact depth through and leave tabs on the last cut. It shows them on the left side of the screen in easel. But for whatever reason no tabs are show on the example piece on the right side. Is that normal or is something not setup correctly.

Can you share project which show this behaviour?
How do you set your work zero? (On top of material?)
Have you calibrated your Z-axis? (Does it move exactly 1" if commanded 1")

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It will not show the tabs in the preview and if you are cutting all the way thru and into the waste board you are cutting them off.

Here are some pics of the spoil board of a pig and some circles I cut out. You can see the tabs in the spoil board. I zero out the z axis touching the top of the material being cut. I have calibrated al axis and there all correct. That was the first hing I thought about. The spoil board was cut about 1/8” deep with the tabs about half that.

Here is a shot of the project in easel. Set for 3/4” board and that’s exactly what I used.

Yeah see my pics posted. I wasnt sure why it was showing the tabs on the preview. It was cutting the tabs in the spoil board.

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The your Z-reference point and overall carve depth is incorrectly matched.

Try a smaller design with 3/4" stock and this time do the following when setting you work zero:

  • Jog the bit down to the spoil board surface.
  • Jog the bit up 3/4" plus additional 1/16"
  • Jog to your intended X & Y zero point (typically lower left corner) and use this as your work zero (home position)
  • Set overall carve depth = 3/4" + 1/16" and choose your tabs.
  • Carve

What was the result?

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Did you check the actual project material you cut with digital calipers? just because you buy 3/4" doesn’t mean it is actually 3/4"

Valid.

When the spoil board is used as Z-reference any inaccuracies in step/mm value is also mitigated.

I didn’t buy it I planed it down to 3/4"

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Sorry I don’t understand what that means. I am using 3/4" thick wood I planed myself to 3/4". If I zero it out on the top of my 3/4" board and I tell it to go 3/4" deep at most it should only go 3/4" and add the tabs on the last pass it makes for the full 3/4" thickness. But it goes through then cuts another 1/8" or so and cuts the tabs in the spoil board.

When you tell the machine to move your z axis up or down 1" does it actually move 1"

yes it does

The 1/8" discrepancy must come from somewhere. It could be mechanical, something slipping or steps lost during plunge/retraction.

If you use the work surface as your Z-reference any backlash component or skewed travel due to not precise $102-value is mitigated.

  • Make a test piece in Easel, set it to 3/4" + 1/16" total depth.
  • Jog the bit down to your work surface, then jog Z up 3/4" + 1/16"
  • Use this as your Z-zero, set manually, no probe
  • Carve

What is the result?

I’ll try that thanks

Okay so I made a test piece of a triangle set to cut 15/16” total which is 3/4” + 1/16”. I zeroed the Z axis at 15/16” or .81 and it went -.9675 every time. So it’s going .155 or 5/32” to deep. I have attached pics of the code and of the axis’.

Tried it with something else I had already setup code for. It also did the same thing. Cut 5/32” to deep on the first pass. So if I have two passes setup for 1/4” it will go 1/4” + 5/32” on the first pass and 1/4” on the following passes.

Could it have anything to do with the bit itself? I know that you can set specific bits in easel which is my design program as well as cnc usb. But I never do. I figured once I zero it to the top of the material it didn’t matter what bit was input.

What happens when you do basic z-axis calibration? Like i you move it up by say 1" (or 25mm if you’re in metric mode), and then jog down 1"/25mm does it move exactly that much?

Yep moves perfectly that way.